Eusebius, Onomasticon 22:6-10 (ca. 295 A.D.); Jerome 23:6-12 (ca. 390 A.D.)
Accaron (Jos 13:3), in the tribe of Dan, or as I believe, in the tribe of Judah, 'on the left of the Canaanites', a city of the five satrapies of the Philistines, which was allotted to the tribe of Judah, but (the tribe) never took possession of it, for it was unable to drive away the old inhabitants. And to this day there is a large village inhabited by Jews, between Azotus and Jamnia to the east. Some people believe that Accaron was the name of the Tower of Straton, later called Caesarea.

BIBLICAL BACKGROUND

Jos 13:2-3 Lands remaining unconqueredThis is the land that still remains: all the regions of the Philistines, and all those of the Geshurites 3 (from the Shihor, which is east of Egypt, northward to the boundary of Ekron, it is reckoned as Canaanite; there are five rulers of the Philistines, those of Gaza, Ashdod, Ashkelon, Gath, and Ekron), and those of the Avvim,

Judg 1:17-19 The settlement of Judah
Judah went with his brother Simeon, and they defeated the Canaanites who inhabited Zephath, and devoted it to destruction. So the city was called Hormah. Judah took [did not take: LXX] Gaza with its territory, Ashkelon with its territory, and Ekron with its territory. The Lord was with Judah, and he took possession of the hill country, but could not drive out the inhabitants of the plain, because they had chariots of iron.

1Sam. 5:10 The ark in Ekron
So they [the Philistines] sent the ark of the God of Israel to Ekron. But when the ark of God came to Ekron, the people of Ekron cried out, "Why have they brought around to us the ark of the God of Israel to kill us and our people?".

2Kings 1:2-3 Baal-zebub, the god of Ekron
Ahaziah had fallen through the lattice in his upper chamber in Samaria, and lay injured; so he sent messengers, telling them, "Go, inquire of Baal-zebub, the god of Ekron, whether I shall recover from this injury." But the angel of the Lord said to Elijah the Tishbite, "Get up, go to meet the messengers of the king of Samaria, and say to them, 'Is it because there is no God in Israel that you are going to inquire of Baal-zebub, the god of Ekron?'

MORE ANCIENT SOURCES

Josephus, Antiquities 9.2.1 (1st cent. A.D.)
Now it happened that Ahaziah, as he was coming down from the top of his house, fell down from it, and in his sickness sent to the Fly which was the god of Ekron, for that was this god's name, to inquire about his recovery:1 (20) but the God of the Hebrews appeared to Elijah the prophet, and commanded him to go and meet the messengers that were sent and to ask them, whether the people of Israel had not a God of their own, that the king sent to a foreign god to inquire about his recovery? and to bid them return and tell the king that he would not escape this disease.

Iohannes Fedançole, Descriptio, 28:4 (ca. 1330 A.D.)In the square 61 is Accaron of which speaks the blessed Jerome... I, friar John got hospitality there. Jerusalem is situated 20 miles east of it.